Send connectors are used to control the flow of outbound e-mails to the receiving server, and are configured on Mailbox servers running the Transport service. These are commonly used to send outbound e-mails to an Edge server, a smart host or directly to the Internet.

With the changes in the transport pipeline, Send connectors now behave slightly different. For example, as we saw in the beginning of this chapter, they can be configured on a Mailbox server (Transport service) to route outbound e-mails through a CAS (Front End Transport service) in the local AD site by using the FrontEndProxyEnabled parameter. This is useful to simplify and consolidate e-mail flow, especially in environments with a large number of Exchange servers.

While using Send connectors to send e-mails out to the Internet, administrators have two choices to resolve the recipients...